1. Field of the Invention
The invention relates to a device for equalizing relative displacements in level between ground areas and frame-provided closing means of installations, e.g. shafts or slide rod assemblies with protective shells, comprising a load transmission element connected to the closing means frame.
With installations in traffic area bodies or, generally, in the ground, such as, e.g., with gully holes, water supply, gas or telephone shafts, or also with slide rod assemblies including protective shells, the uppermost closing element parts, i.e. the shaft lid or road caps, e.g., will be raised or lowered relative to the traffic area upper side. This, i.a., is due to the fact that a gully hole, e.g., is located at a level substantially below the conventional frost line. Thus, the shaft bottom will not be affected by the influences of frost or thawing, respectively, which cause swellings or shrinkages, respectively. Such swellings or shrinkages, however, do occur in traffic area bodies, e.g. road bodies. As a consequence, a relative difference in level between the road surface or, generally, the upper face of the traffic area and the shaft system will be found, causing bouncing to vehicles rolling thereover, and possibly even causing damage to the vehicles themselves. Moreover, as a consequence of such irregularities in level, a damage to the closing means proper, the lids or the like, may occur, possibly even leading to the destruction thereof and necessitating complicated repair work. Another possible reason for such relative movements of level are, e.g. settling events in the soil.
Movements in level may also occur in ground regions on private property, possibly also in planted areas, yet in most instances traffic areas, i.e. roads, parking spaces etc. are affected.
The said relative shifts in level or dilations are primarily caused in the region of the so-called frost road bed construction of road bodies, with gully lids, e.g., lying at a lower level relative to the road surface in winter, whereas they protrude from the road surface in summer.
2. Description of the Prior Art
In CA 1,289,799 C, a device as initially defined has been proposed, in which a floating support of a shaft cover is sought so as to attain a vertical movability thereof. In detail, the shaft cover is put on a tube part which externally telescopically overlaps the shaft. On the jacket face of this tube part, annular grooves or ribs are provided for an improved non-positive engagement with the surrounding road body. This tube part thus is conceptioned as a load transmission element to entrain the shaft cover in upward direction during a shift in the level of the road body. In fact, however, this known construction is not suitable for such a dilatation equalization because in possible movements in the road body, the material of the road body will tear off in layers. Apart from this, as a rule, the substructure material in the immediate vicinity of a shaft will not freeze even at freezing temperatures—and thus there will not be any substantial movement of level since the shaft will raise the temperature. in this immediate shaft area.
Besides, also shaft constructions are known in which, when traffic areas are provided, an upper telescope-like shaft part is to enable an adjustment of the shaft height to the surrounding traffic area level, this telescope part being tightly anchored when it is installed, for which purpose, e.g., a site-mixed concrete layer is provided around the telescope part, cf. in particular AT 403,42 B, but also U.S. Pat. No. 4,936,703 A or U.S. Pat. No. 5,044,818 A. A dilatation equalization is not sought with these known installations, and it is not possible, either.